Cartridges for use in the preparation of beverages are well known. For example, it is known to provide a cartridge for use in a beverage preparation machine which, in use, is pierced by a piercing element of the beverage preparation machine to allow hot water to flow through the cartridge to brew a beverage medium such as roasted ground coffee.
US2010/0303964 describes one such cartridge including a container, a beverage medium, a filter and a filter guard. The filter guard is arranged to be contacted by a piercing member and thereby be displaced upwardly during use. Displacement of the filter guard during use causes distortion of the filter and the beverage medium that may lead to inconsistent brewing of the beverage medium. Disruption to the beverage medium can lead to the formation of crevices in the beverage medium during brewing which allows the hot water to preferentially flow through the crevices rather than a uniform bed of the beverage medium. In addition, the need for the piercing element of the beverage preparation machine to displace the filter guard increases the force required to close a brew chamber of the beverage preparation machine and may also lead over time to blunting of the piercing element.